Never really liked any of the series that much.
The much-vaunted atmosphere didn't cut it for me. It came across as a clumsy pastiche of Aliens
In defence of AB3D, though, it must be pointed out that the thing was designed for an incredibly low-spec machine. Same goes for Gloom. Doom has higher requirements, and has more detailed gfx as a result.
Slightly OT: Chicken and egg situation. Softcos presumably thought it pointless to develop games that required accelerated Amigas with extra mem, or even a graphics card, as the volume of sales would not justify it. Amiga gamers didn't have enough incentive to upgrade their 2MB machines en masse, as the games weren't there to take advantage of the extra power. By the time AB3D2 was released, Quake was out for PC, and the gap in typical system specs was well established.
How did the PC market manage the feat of making people upgrade in order to be able to play a game?