I have stuck with standard E, but just got a new guitar and will be drop tuning So I read through some reviews, on the Boss Tu-2, Korg pitchblack, and the cheaper non-pedal Korg CA-30 and to the much more expensive Korg dtr-1000. I understand a tuner is a tuner.

If I change my tuning a lot would one be easier to use than the others and be more accurate?

I also don't know if it would be worth it to pay more now rather than later?
Unless you're gigging, you don't really need a pedal tuner.

I have that ca-30 and it works fine. Turn amp on to warm up, tune, plug back in to amp and play.