Floor tile question

[Worriedandonedge]

I'm hunting online for tiles for my open plan kitchen / living / diner extension.... vast differences in prices for what look like similar items. is there anything particular I should be looking for in tile specs? Is there a minimum depth that's considered decent quality?
Thanks! (Same for outside - should I only be looking for 20mm for outside depths?)

So have done this recently for bathroom tiles and this is what I learnt:
~The bigger the tile the more expensive it is but the cheaper it is to fit. Sadly I don’t know the point at which it flips in terms of cost.
~Tiles that are labelled as having rectified edges are more accurately made and can therefore fit closer together with less grout. Unless you are making a feature of the tiling this looks much nicer. And obviously there are benefits to having less grout.
~there is quite a bit of price overlap between the nicer stuff at your well known tile warehouses and the more affordable stuff at your more aspirational (well for me at least) retailers. I found the advice better at the latter and they were open to some negotiation on price.
In the end I walked into Porcelainosa with my floor plan, my budget and some thoughts on what I did and didn’t want (colour, finish, slip level etc) and we found a really good solution. And they matched the grout!

Thank you @Procrastatron, really helpful!

@Procrastatron thank you this is very helpful!
Were you able to visit porcelainosa in lockdown? Looking for a wood look tile for the kitchen / lounge as well as doing 3.5 bathrooms - full house reno - finding challenging in lockdown

Looking at my emails I went in September last year and I guess things were more open then so I don’t know about right now. Are you London based? Bathrooms by design supplied our bathrooms and had the wood effect tiles available but sadly DH vetoed them. I would fully expect Porcelainosa to stock them too though, plus they have their absolutely massive warehouse in Watford so you can pick things that don’t need to be shipped.

@Procrastatron yep I am north London based so know of porcelanosa in watford just didn't get a chance to check out bathroom or tile places before the last lockdown - thankfully got to look at kitchens but now I'm researching mostly online!

Ask for a discount! We got 20% because we asked about our place of work, they didn't check, albeit it was true