Administration burden
Write the name of the person who will own this system in twelve months. If no such person exists, and none will be hired, then configurability is a liability rather than a feature. Every setting you can change is a setting somebody must decide, test and maintain. Prefer the option where a sensible default exists for everything and where a change takes minutes rather than a support ticket.
Total cost over two years
Software is usually the smaller half. Add calling minutes or telephony integration, messaging charges where they apply, storage for recordings and attachments, any middleware needed for integrations, and a realistic estimate of internal hours spent on setup and maintenance. Ask each vendor to confirm the seat count, the add-ons and the renewal terms in writing so that your total is built on quoted numbers rather than assumptions.
Channel coverage
Ask yourself where your last twenty customer conversations actually happened. If a meaningful share were phone calls and messaging threads, then a system that captures those automatically is not a luxury, it is the difference between a record that reflects reality and one that reflects only the parts somebody remembered to type in. Test this with a real conversation during the trial and check what lands on the lead record without anyone doing anything.
Reporting you can build yourself
The reports that get used are the ones a manager can build at the moment they think of the question. If building a pipeline review requires a ticket and a wait, the question gets abandoned and decisions get made on impressions instead. Test it directly: give yourself half an hour to build your weekly review report from scratch, unaided, in each candidate system.
Migration and exit
Import a few hundred genuinely messy records during the trial, duplicates and all, and look carefully at what happens. The clean-up you observe is the clean-up you will face at full volume. Then run a full export and open the files. Knowing how easily you could leave is the most reliable way to feel comfortable staying.