If you want a GPS / HRM watch your options are Garmin, Suunto, Corus and if you don't mind a brand that is slowly dying away Polar. I don't think Suunto really has lower end models - their niche is sort of adventure sports like ultra trail racing and mountain climbing. Corus is basically an alternative to Garmin if you want a top end unit but don't want to spend $600. I've not looked at their full product line but I do know they have some nice units that compete with the Garmin Fenix line. There is nothing inherently wrong with Polar units if you can still find them.
If you want a good, entry level to top end HRM /GPS Garmin is the way to go." Garminconnect" is their application you can use for tracking workouts and your overall health - went down last summer for a few days, never really heard why. Garmin sells Bike computers bathroom scales and a full suite of related kit that you can use for other sports. Personally, I don't want to use multiple software applications to track running/cycling/swimming workouts
I'm sure others in answering your post have good suggestions for an entry level unit. I've owned a Fenix 6X sapphire for about a year and it's been rock solid with wicked long battery life but its well above your desired price point. One thing you would want to do is buy a unit that has been released recently to make sure you get all the most current bells and whistles and the newest sensor technology. DC Rainmaker has the most through YouTube product reviews and he's pretty objective