I have had large upright larder freezers for many years up until I moved into my flat. Last one purchased only ten months before I actually moved, and had to then sell that on, as no room in my new kitchen.
Make a note of the space you have so you no the maximum width freezer you can have there, check if you will need to have door opening side changed (most companies charge extra for this).
Main things to look for (IMO) -
1. Must be self-defrosting
2. Drawers (not flaps). Some drawer fronts are incredibly fragile - and do break easily - this needs to be checked out.
3. Signal, either light or buzzer (preferably both) if door not closed properly
4, Do you want one large larder freezer? - you can get some that divide into two separate areas now.
5. Check actual capacity - some look large but have less capacity than others that look smaller.
Start with looking into Ao website, where very good, detailed information on many freezers can be found.
Note the ones you think are appropriate for you. Then go (when they re-open) to any large retail shop and have a look at them 'in the flesh' so as to speak.
Once you know the make and model number of the machine you feel is right for you - start a good web search for best buy, taking note of delivery charges, etc.
Freezers are one of the few 'whites' I think it is worthwhile having extended warranty for.
Personally, I do not think it is a matter with these that you get what you pay for. Prices range incredibly
Best to go for middle of price range and do your comparisons very carefully to see what you are getting.