Everyone has their scale likings ^_-
The deluxe class just happens to be my version of “fun size.” The scale feels good in my hands and is fun to play with without feeling like it’s going to break… most of the time xP
I actually enjoy the Commander Class guys, for the most part, but I still find more enjoyment with the deluxe’s and voyagers (the chunkiness of the latter is oddly appealing xD ). The side of me that’s frugal & something of a scale whore gets annoyed when a figure that’s half the size is just about the same price xP It just makes me feel like I’m getting less “bang for my buck.”
The leaders do for me what the commander class does. Though it’s not so much the “less bang for my buck” thing as it is a “that’s a crap ton of money.” If I kept to my monthly play-budget it would mean a month and a half of saving to buy the thing… yeah, I’m working on the anti-splurge thing this year. Lol. Still. I own 5 Leader class figures and of them I only paid full price for 2. The other 3 I got for 50-75% off and of the two Ultimate's I have I paid $8 for one (used, fully functional and will all pieces except the missile accessory) and $50 (new) for the other.
Legion class wise… they feel awkward in my hands and I dislike the lack of articulation. I’m more OK with the lack of elbows than the lack of knees though.
I own a few legion’s from the DOTM and HftD lines but I’m only really happy with HftD Optimus, Starcream and Megatron. I found them to be a lot of fun transforming and they are aesthetically pleasing, even if two of them lack knee joints. DOTM Soundwave, the ROTF repaint, I thought had a fairly nice robot mode but I dislike the satellite form and the transformation was boring. I’m impartial to Rodimus and Bee who came in the set with him (I honestly only picked it up because it was $4 or $5 and I thought I’d give the tiny guys a shot since I was getting 3 for the price of 1). Same goes for HftD Prowl. I didn’t think his design was all that great but since I enjoyed the other from the line I thought to give him a shot. Yeah, he kept me from buying Trailcutter.
The Deluxe and Voyagers may take up more shelf room but I’d rather have a higher enjoyment level than more figures per shelf. You enjoy the mini guys so it works out all around for you xD Me, I’ll find room for my bigger, more bulky dudes

And I have to, considering I also collect somewhat fragile Tin Toys that run the same size (and bigger) x3 I'm excited to be getting a newer (bigger) room xD More shelf space!