That's a bit like asking I just bought new running shoes, what type of socks should I get - it's impossible for anyone to answer but you. Everyone is different, so what works for one may not necessarily work for another.
Best bet would be to try what you are using at the moment. If you can play the whole range of the instrument without any major difficulties, then the question is answered - stick with the reeds you have. If the high notes come out cleanly but the low notes are difficult, try stepping down in reed strength. If you find the low notes are easy but the high notes close up, then try stepping up in reed strength. If after trying a few different strengths it is still difficult to blow, then try different brands. If it is still difficult to play, then it may not be the right mouthpiece for you.
One thing I'd suggest is to use different reeds for each mouthpiece. If your previous mouthpiece was not completely flat, then reeds used on that mouthpiece may have slightly distorted to fit the mouthpiece's imperfections. Those slight distortions (if they occurred) that made the reed fit perfectly on one mouthpiece can cause havoc on a different mouthpiece.
Have fun, as you've just entered the quest to find the perfect mouthpiece/reed combination - a quest many attempt, but few complete. After all, if such a combination existed, we would all be using it. 🙂