Pick one and stick to it for 1-2 weeks to see if it works for you.
As in, you're retaining things, and also you're able to focus with using them consistently. Indicating that you're actually able to be committed to say..doing 200 qs a day for FC or something. if you can't, you can't. try osmosis or something else then. All you've lost is a week or so. If they're both giving you results, just pick one. If you get sick of it, switch to the other one later.
It's not like any of them are mandatory parts of your curriculum. You're allowed to have a personal preference and not like something. You're also allowed to change that personal preference later, depending on how your study habits change.
Just don't use them all or don't use both at the same time to study the same things. your time is precious. as is your $$$
There's so much review material out there in general, you'll never be able to try them all, and it doesn't matter either. All that matters is that one works for you and you like it. IMO anyway.