Obviously Raven
While some may argue that Raven was not underrated, having won heavyweight gold in ECW and TNA and championships in WCW and WWE, which not many other wrestlers have done, the man is so talented that he should have achieved alot more than he did, and I think alot of that is down to WWE and WCW under-rating him and not allowing him the chance to spread his wings.
Raven is one of the true masters of the promo, and too few people realise this, due to his lack of opportunities in WWE, where he was basically made a jobber at the time of his most exposure. He is captivating on the mic, and one of the best storytellers in the business. WWE missed a huge opportunity when they failed to utilise Raven's talents, and a gimmick which was unique and revolutionary in the wrestling business. He is under-rated by a lot of fans because they never saw him in ECW and only have memories of him struggling in WWE and being rooted in mid-card level in WCW.
Bagwell on the other hand never impressed me. He had a phenomenal physique, which will always get you somewhere in the wrestling business, but he offered little else IMO. I think he did as well as he should have in wrestling, and people think of him at the level that they should. An average mid-carder
who wore a stupid hat