Possibly odd but interested to hear what others think based on visual alone.
My bike on the left (ti frame, running a Singular Swift fork for winter, usually have a SID 100mm), friend's on the right that I'm borrowing so saddle set to my height. Had my bike a good few years, like it and find it comfortable (singletrack and xc type stuff), and light. Friend's bike instantly felt a bit bigger but within 10mins, felt 'right', comfy, smooth, fun. So, assumed my bike was 'wrong'.
Rode both back to back and within 10 mins of riding the other bike, that bike felt good. So despite different frame sizes, real life suggests not a lot in it.
Just from looking, does one look more 'right' than the other? Does friend's bike look more modern?
Bottom line is, they're both fun and good!
Oh, and I'm running a Singular Swift fork for winter, summer it's a SID 100mm
Most people can ride more than one size of bike and “right” is a moveable concept.
Beyond that I can’t help much, but I wouldn’t let it worry you.
You're “bottom line” was probably spot on.
does one look more 'right' than the other?
At a glance, Nope.
People are actually quite adaptable, if you’ve set the seat at about the right height the bar height/reach can move by a substantial amount before something is “unrideable”.
Your Mates bike looks to have a much longer wheelbase (mostly due to a longer front end) with a slacker HA, but also looks to be a size or two bigger(?) so it probably felt a smidge more stable descending/at speed? But I bet your own bike feels very different once you slap the SID on for summer too.
Personally (and with the limited info of only looking at a photograph). Apart from the saddle and stack being too low for me, the bike on the right looks like it would suit me much better than the one on the left.
But obviously that means very little
Mrs_oab's Merida e-hybrid looks really old geometry. High and nearly level top tube etc. it constantly looks like a medium frame.
But when we peeked at the geometry charts compared to her previous bike, Marin hybrid which looks tiny with dropped top tubes and off set tube junctions etc, it's only a few mm in it.
I think you are judging on aesthetics as much as geometry. I personally also find a wee tweak of bars and saddle can really change a bikes character and comfort.
I'd rather ride the one on the right as it has suspension.
That's my bias. I had a go riding my gravel bike with a rigid fork round the Sherwood pines red. It was no fun for me.
lawn a bit mossy but actually in pretty good shape for this time of year
Chuckling at the lawn comment ... 3 spaniels and multiple squirrels burying walnuts don't help it much!
And comment re aesthetics is bang on I think ... if I rode with my eyes shut (assuming both had sus fork), I think it'd be hard to spot the difference ... poss one being lighter and touch more nimble ... but not a huge difference
the one on the right is significantly longer in wheelbase and slacker in the head angle (the rigid forks make it look slacker than it is too).
from a fit perspective they look pretty similar so makes sense that you will be able to comfortably ride either. the handling will be a significant change between them, although neither is "right" or "wrong" they will have their positives and negatives depending on terrain, riding style and riding intent; and more importantly people will have their own preferences.
How did yours feel when you got back on it?
Looking at the geometry, the one on the right looks like you are in a slightly better pedalling position given the the steeper STA & will be more stable at speed, but you need to get your forward to make the most of it, compared to your usual bike.
But both look like fun bikes.
I'm maybe alone in this here, but I hate geometry where there's a chance my front foot can touch the front tyre. So based on that alone I'd grab the bike on the right.