Venom. Dude's existence, as a symbiote, is predicated on being a rip-off. Originality is key.
Deadpool. Always 'liked'. Never 'loved'. I think he's hysterically overrated. Cringe-worthy a lot of times.
Phoenix. As a historically big X-Men fan, I just don't get the hype. So many better villains and stories.
Green Arrow. Never understood his popularity and inclusion in the JL.
Any female copy/rip-off ever. Original female characters are always better.
For the record, prior to the New 52, I don't think anyone "loved" Aquaman.