Depends on the budget and how exactly you're planning to practice. I have tried bunch on different headphone practice units - Korg PX4D, iRig, Positive Grid(BIAS), Line 6 Sonic Port, Tascam GB-10, Line 6 Bass PODXT, Line 6 POD X3, Ampeg SCR-DI and Zoom B3. So yeah, I could talk a bit about all of them

as I play in church, I need to have access to computer - we have a large library of songs and we introduce new songs quite often as well as key changes. Tascam was a pretty good unit, but as mentioned above, I had to go to computer to put new songs on it all the time. Tone wise it's just meh. Ampeg has great tone, but I really didn't use it for more than just practicing(I play through REDDI at church), so I could justify that much money invested to a pedal that I don't use live. In the end I ended up with POD X3 which was the best option until I got Zoom B3. It's the best option for me - it has great tones(it can be absolutely clean and uncoloured), really versatile interface, drum machine, looper and is quite cheap! I'd say it's the best bang for your buck - you can bring it to any gig, use it is DI or as stop boxes, you can practice with it at home. I wish it would have additional AUX, so I might stay away from computer, but I could live without it. Again, it all depends on your particular situation. If you're fine practicing from your MP3 player/smartphone AND need a preamp/DI, then Ampeg is your best bet. If you want to save some cash, go buy used Zoom B3 and buy another pedal(or two)