The SVT model in the AxeFx is for all intents the only amp model that made its true bona fides as a bass guitar amp, although there are a few others that can yield very good results, depending on what you are looking for. Vintage tones out of the Bassman models can be used since the virtual world allows you to amplify the "good parts" of the tone without having to deal with the "bad parts" that rear their ugly head when using a REAL Bassman (not loud enough to keep up, and things start to "flub" out). The Hi-Watt simulation can also be pretty cool. Another neat trick is to engage the SVT amp model, but then go into the Tone Stack type (advanced parameter) and change it from Passive (default) to one of the many other tone stacks available to you. Really a lot of options, depending on what you like, and how deep you want to go into the unit.
Some users don't even bother with cabinet simulations (or even Amp simulations) and rather utilize EQ blocks, compression (and/or multi-band compression), Drive (pedal) blocks, resonator blocks, etc. That's the beauty of the AxeFx: so many different tools at your disposal. The key is knowing what to do with those tools.
