Firstly I would look at what your current gel brand offers. Their builder gel will be most compatible with the gel polish you already use.
And once you've decided which you'd like to use, make sure you have a proper look at their specific prep routine. When I switched from a White Bottle brand, it was a massive shock. Before, I could literally do my cuticle prep and give the nails a half-hearted buff. So when I moved to CJP and my sets weren't lasting, I thought it was a bad product. Once I'd cracked their prep routine, it's been so much better.
I'm almost exclusively CJP / CJelp now and use these products
B.O.B (Brush on Builder): Available in I think 15 colours. No base coat needed. Just prep and dehydrate. Recommended for extending, as it needs to be quite thick otherwise it cracks. However I do overlays on nail-biters on their first appointment with me. Yes they are a little bit thick, but it's what they need to push through those first 3 weeks of growth and get their free edge back. They don't tend to catch at that length either so I don't have any issues. There's a detailed video explaining how to use BOB. Although advertised as "soak off", I would class it as file-off. I very rarely remove BOB now and just infill every 3-4 weeks..
"Rubber It" : Basecoat for Bob. For BOB overlays, add a layer of rubber-it first. It gives BOB the flex it needs to stay put on short nails.
Can be used alone as a basecoat for gel polish. This one is great for weak/thin nails. It's nice and flexible. Rubber It can be filed down and infilled but also soaks off easily,
All About the Base: Very similar to Rubber It. Same application and removal steps. Can be infilled. Has a pink tint, and 2/3 coats make the perfect French base. Ideal for healthy nails.
