Hey Ben! I've been an agent in Maine for 11 years and have experience with both agencies. There are pros and cons of each. I personally just switched to eXp after running a local agency for years.
I think one big difference is that KW has brick and mortar locations, where as eXp is all online. They occasionally have offices here and there but nothing like a KW building. KW offers a lot of in person training where as eXp is focused online. I think with the way our industry is moving, everything will go online and that's why I made the choice I did. It's better to be ahead of the curb.
eXp also has some other great benefits. The whole network is ONE agency. So if you want to get licensed in 4 other states, countries, etc, you can and you'd work all under the same single agency. No having to find a KW branch in each different place you want to sell.
Lastly, they have a 3 free closings thing where I can sell/buy 3 buildings that I'm part of the sale of (as a buyer/seller) and I get a 100% commission split. Plus, after you hit $16,000 paid to the agency in commissions, you go to a 100% split with just some small fees for closing preparations.
Ultimately, it's a question of where you're at as an agent and what your preferred method of learning is. If you're okay with doing thing digitally, I'd say stay ahead of the curve and go with eXp. Feel free to DM me if you have questions! Good luck.