My personal recommendation is to always separate the modem from the router. Makes it easier if you need to replace one of the features. So my advice is to go with separate devices.
Couple of questions.
1. Do you see yourself upgrading your speeds in the future?
If so, it might be best to get one of the newest modems. DOCCIS 3.1, 32x8 modem. I had originally bought the Motorola MB8600, but had to return it because I needed a modem with Voice compatibility, and this one doesn't have it. I ended up with a Netgear CM500V, which is only 16x4. You don't need phone compatiblity, so the Moto8600 would be a good buy.
2. For the router, do you need parental controls? Time Machine? Mesh? USB?
I went with Synology RT2600ac because I wanted parental controls, Time Machine support, NAS support, easy mesh capabilities, and usable USB ports.
I looked at Linksys Velop, Netgear Orbi, and the TPLink Deco. They all kinda-sorta met the bill, but had a fatal flaw here or there that drove me to the Synology.
Linksys - many reviews about signal drop out
Netgear - parental control is exclusively via Disney Circle. Didn't want that in my set-up.
TPLink - the USB ports on the device aren't activated ... therefore useless for the USB printer I wanted to plug in.
I've been pretty happy with my Synology. The set-up is straightforward, but a little confusing. There are different login and password "accounts" that aren't fully explained at the time of set-up. When you add a NAS into the picture, it get's a little more confusing. But I muddled through.