Every test-taker is different, of course, so what works best for some may not necessarily be the best approach for others. That said, I'd recommend doing both, but be methodical about it. Over the course of a week of practice, it's good to cover both verbal and quant so that you're up to date on each, and you don't let anything fall by the wayside.

It's ok to stagger them out, though: e.g. verbal on Monday, Wednesday, and Friday, and quant Tuesday, Thursday, and one day over the weekend. This works particularly well if your study periods are short, say an hour or an hour and a half. If you're studying for longer periods at a time, then it can be fine to mix it up even over a single day. What you want to avoid is a situation in which you've been studying verbal for 3 weeks, but you've forgotten all of the quant that you picked up along the way!

I'd also recommend consistent vocabulary review, no matter what else you're doing. It's easy, doesn't require too much thought, but comprises a large part of the verbal section--plus, it's always important to build up a solid vocabulary! Whether you're using flashcards, word lists, an app, or some other approach, keep this going as background review. You might also do the same for basic math concepts, if you need them (you can use flashcards, cheat sheets, etc)

Hope that helps!

Steve