I would not overthink it too much, especially starting out. You PLAN to have 100k visitors, and while it's a great goal you likely do not want to spend the money for the size hosting now..
What's your budget?
As someone said do not use Hostgator/Bluehost (Any EIG company, just google it). Most shared hosting will work for some time and here is what you can do:
- Domain needs to be kept separate so you can easily change(I use Namesilo mainly, heard Porkbun, and also used Dynatdot, do NOT use Godaddy etc)
- Use a plugin for daily Offsite Backups of your Wordpress installation so you can easily install it on another server
- You NEVER get truly unlimited anywhere...Imagine Amazon-like traffic running on shared hosting for $5 per month? Every host will have limits on inodes, CPU usage etc... even if they say unlimited storage/traffic you will soon realize that won't be the case
- Use a caching plugin (or do your own CDN if you want to for say just images)
- For the rest of the files just use free Cloudflare for now
Where do you think your traffic will come from? Most people make the mistake and say use gtmetrix or pingdom with a server that is very close to their hosting, e.g. NYC, but yet 90% of traffic comes from the West Coast... For which a West Coast host , or a true CD/load balancer etc will be better...
I used Hostwinds here before but they got sluggishly slow, always had a billing issue and now are expensive for the kind of hosting they offered, never used another host from the forum here.
I'd say go with one that you think will not shutter tomorrow, keep backups, and likely you will be ok to start with all of them. Don't pay 1 yr upfront without testing (Siteground has setup fee if you just choose a month so I did not use them).