If playing on the TV is important to you, get an A330 and a wireless controller; if portability is important to you, get an A320. I have both; I carry my A320 around and use my A330 only as a home console, but that's just my preference. One reason is that the "A" button on my A330 doesn't work very well, so using it as a home console with the wireless controller works better for me; also, the shoulder buttons on the wireless controller provide a better play experience for SNES and GBA games. Sure, you can use an A320 as a home console, but it's kind of awkward given the TV-Out socket placement and the tiny, fragile shoulder buttons.
Emulation is similar between the A330 and A320 except for the NEO GEO and the GBA. NEO GEO works perfectly on the Dingoo Digital A320 but not on the Dingoo Tech A330 (or Dingoo Tech A320). GBA on Dingoo Digital A320 has better compatibility (including Jungletac games) than Dingoo Tech A330 (and Dingoo Tech A320). Apparently, there are some differences in the 3D games, as well, but I'm not certain.
Should owning a DS Lite prevent you from getting a Dingoo? Well...can a DS Lite emulate the GB, GBC, GBA, NES, SNES, Master System, Game Gear, Genesis, Lynx, Turbo Grafx, CPS1, CPS2, and MAME systems? If you want to play games for these systems and more with one unit, get a Dingoo (Dingux opens up even more possibilities but is not necessary). The Dingoo is also has a video player, music player, FM radio, and more.