Of the most recent ones i have to say GTAIV. I loved all the other GTA, but this one felt so plain and boring, i couldn't get myself to finish it yet.
As for the classics, my vote has to go to FFVI. Don't get me wrong, i love the game, and to me it has the best OST of every FF game. But after the masterpiece that was FFV, FFVI felt very shallow and uninspired, and if it weren't for Kefka, Celes and Cyan history and character development, then it would have felt plain in the character department.
(also to the poster who said all sonic games are bad, including Sonic 1, 2 and 3...you clearly have no taste in gaming whatsoever.)
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
