You really need to see and try them but if that's not possible read some reviews.
The Merida has quite an upright riding position so comfortable rather than sporty. It's a 1x drive so you won't have the spread of gears on a double or triple and you'll have bigger gaps. Frame welding and finish look rough. Internal cable routing looks good but can become problematic after time with cables making contact with the frame.
The Topstone 3 is a bit more sporty despite the relaxed geometry and the double chainset should make it easier to fine tune the gears. 105 drive is fine but the cheap FSA chainset is a disappointment due it's reputation for failure. I think the BB is pressfit , again not the best for reliability, I would recommend avoiding anything so fitted, threaded is a better bet.
Sorry to rain on your parade but there are many aspects to consider so maybe do a bit more research.
That Boardman linked above looks good VfM so maybe worth a look. Might be a better choice if you're going to be spending more time on tarmac.
Be aware a gravel bike won't be so nimble or quick as a road bike on tarmac.
Always a good idea to post a link to the specific bike to save us from scrambling around googling and to pinpoint the exact model and specs which can change
Whatever you go for I'd buy locally rather than on the interweb, if anything goes wrong or needs adjusting you've got help at hand.

to the forum.