I like Eleaf's products and especially their prices. I have an old iStick 20W that's been everywhere in my pocket and has the scratches to prove it. It still works as advertised and produces a good, dependable vape.
I lost some faith in Eleaf a couple of years ago when I bought one of the earlier iStick 50W mods. I loved the design, the feel, and the performance, but two of them died with failed displays within the 90 day warranty period. I haven't bought an Eleaf mod since.
Now, I'm also looking at iStick for an inexpensive TC mod, but I'm leaning toward the Reuleaux RX200. I'm not sure if I want a triple 18650 mod and the case is kind of funny shaped with the batteries in an arrangement that makes it a little fat. That said, it gets good reviews. The RX200 is user firmware updateable from a computer.
My Smok Koopor Plus 200W that requires the user to buy a Eprom burner for $30 to do the update. In it's V1.002 firmware version it won't do TC properly. It's so hot that it can burn your tongue. TCR settings don't fix it.