I've heard others mention the high rate of juice consumption on the tfv4 especially with the quad coil head installed. Typically the more coils/wicks the faster it goes through juice, for cutting back on juice consumption maybe a dual or single coil? Can't really speak much for the tc100w, I've only had mine about a day and a half. Loving it so far but haven't used it long enough to speak about its durability/longevity.
You're right, it's a bit of a brick but thankfully is rounded so seems to fit the hand good. I like that it has the tc option as well as the option to run single or dual batteries. Seems pretty solid to me so far though, no glitchy issues, no rattles. The only problem I had was when I first attached my new rta. Kept telling me atomizer short but that was my fault. My coil was up just a little too high I think, I pushed it down a hair and no more fault codes. (hey it's working as intended right? lol - user error, doh).
Can't say whether the ehpro bachelor is the best rta out there but I like that the tank comes off the build deck without leaking. Earlier I wanted to sample some juices and instead of washing the tank out over and over I just rewicked it with a fresh wick. Saturated the wick, screwed the tank portion back on and basically used it like a half assed rda. Made sure the juice flow was closed and just vaped what was on the wick. Wash rinse repeat through the flavors taking just a minute to rewick in between flavors and a few quick pulses to glow the coil and burn off the old flavor. Sometimes ya just gotta get creative lol.