Currently the most prestigious:
(p.s. - Due to my lack of cable, I don't watch TNA, so I can't rate how prestigious their titles are right now)
1. World Heavyweight Title
The match at Wrestlemania between The Undertaker and Batista set it off for me. The Undertaker won the Royal Rumble and chooses to take on Batista instead of Cena. These two men had a classic back and forth match that resulted in The Undertaker coming out victorious over a powerful Batista who had torn through the Smackdown heels one by one. It took a Last Man Standing match, a Cage match, a Mark Henry beating and Edge stealing the Money in the Bank from Ken Kennedy to cash it in at the tail end of the Cage match, and still it took more than one spear to put him down. Now Edge is holding it and keeping it from Batista with every trick in the book. This all, by the way, has been the past three months for the belt.
Last year, Rey Mysterio wins the Royal Rumble and chooses to face Kurt Angle for the World Heavyweight Title. The year before, Batista chooses Triple H. Every year the Royal Rumble winner chooses the World Heavyweight Champion and not the WWE Champion. That alone makes it more prestigious. The legacy behind the actual title belt itself speaks volumes, but we're talking currently.
2. United States Championship
A belt that MVP chased for 3 PPVs. A belt that helped popularize Chris Jericho, Goldberg, Scott Steiner, and Bobby Lashley among others. MVP has a chance to establish himself with the U.S. title. He got a very credible win over Chris Benoit and can now run with it. I think the belt is already well-established and is a major part of the Smackdown show. Think about this, JBL was WWE champion, lost it, and won the U.S. belt, and he didn't lose much credibility. Same with Booker T, Ric Flair, and Big Show. If you're not at the top, the U.S. title is the belt to have to stay on top of your game.
3. WWE Championship
I'm not crazy about the Spinner version that John Cena adopted (and Edge used as well). I remember when Hulk Hogan spray-painted the nWo on WCW World Title, and how hard it was to get the belt off of him, and the big deal it was made when he finally lost it to clean off the graffiti. Why hasn't a heel (or anyone for that matter) done what JBL's feud was a few years ago, which is try to restore the belt from the spinner? Also, the WWE title today is a little below because while it has been retained more than the World Heavyweight Title (there have been 6 WHCs in the past two years compared to 3 WWE champions) the quality of match has gone down. Undertaker/Batista stole the show at Wrestlemania, and none of Cena's WWE title matches have been that epic and legendary since the One Night Stand match vs. Rob Van Dam. Cena has beaten monsters like Umaga and The Great Khali, but neither of them are that credible despite their size and gimmick. Since the brand extension, I don't remember any Royal Rumble winner going after the WWE title (look at WM 19 and beyond). I'm not going to say Cena should lose the belt, but I do think it would be taken more seriously if it didn't spin like a set of rims and more credible contenders were going after it.
4. World Tag Team Titles (RAW)
They were buried a little when Michaels and Cena won them from Rated RKO (why didn't they have Shawn at least wear his Tag belt for Wrestlemania? He was still a champion) When the Hardys won them, at least a legit tag team held them. Now, another legit tag team, Cade and Murdoch won them. With the reunion of Haas and Benjamin, and with London and Kendrick now on RAW, let's see where they go from here.
5. WWE Tag Team Titles (Smackdown)
London and Kendrick held them for a crazy amount of time. Deuce and Domino recently won them. Now the Major Brothers are on Smackdown. (WHO?!) I hope they can at least entertain the people a little. Are there any other tag teams on Smackdown at all?
6. Intercontinental Championship
This was always my favorite title growing up. Guys like Mr. Perfect, Bret Hart, Owen Hart, The Rock, Stone Cold Steve Austin, and a lot of others made this belt the title to have. It was prestigious enough to be fought over without the hype of being THE champ. Basically the Intercontinental title was for those who were A. getting ready to rise up to the top, or B. ready for a major push to see what they had. There was a time when the IC belt was passed around like a NYC hooker in a corporate meeting (i.e. - The Godfather was IC champ once? Road Dogg? Billy Gunn?!) but it was re-established with Chris Jericho, Rob Van Dam, and even Goldust in his heyday. Now it's held by an unknown guy who won it from a cannibal who never defended it. Since 2007 began, Umaga defended the belt maybe once or twice, not including when he lost it. Why no one else has held the belt since then is beyond me.
7. Women's Championship
Thank you to Melina, Lita and Trish for giving the Women's division some credibility. Although pudding match, bra and panty matches and tear-clothing-off matches don't help but raise the male libido (mine included), I have to admit there are some great athletes among the Divas. The Women's championship already has more screen time than the Cruiserweight championship. If the ladies take wrestling seriously, they will put on some entertaining matches the way that Trish, Lita, Jazz, Victoria and Mickie James among others did back in the day.
8. Cruiserweight Championship
Poor Chavo. With Gregory Helms out and most of the Cruiserweights injured or out of the company, he may as well bury the title out to sea. Why not have Johnny Nitro back on Smackdown to at least give him competition? Don't get rid of the title; just hire more cruiserweights. There's gotta be some out-of-work luchadors and Japanese wrestlers somewhere. Couldn't Flair lose some weight and go after it?!