Top 4 easy to learn/Play Mechs ranked in no particular order.
I tried to pick mechs that are good all a rounders, and not locked into one specific build.
First of all these two websites are going to be your best friends
https://mwo.nav-alpha.com/ - Lets you build mechs, search by quirks, and browse weapons as well
https://grimmechs.isengrim.org/ - lists most of the "Meta" builds, and is a good starting point to look at new mechs and what they can do before buying.
Now on to the Mechs
Im starting with IS Mechs, since they tend to be a bit more forgiving than their clan counterparts
Warhammer 6R -
Brawler. A good starter heavy that can do multiple builds, the Warhammer is a staple in pretty much all Battletech/mechwarrior/TT games. The 6R is arguably the best of the bunch, able to do both burst DPS ballistic and laser builds. It's tanky enough to be a front line mech, but it's better suited to a support role. Find a buddy, support them, and apply pressure when needed.
Starting build -
https://mwo.nav-alph...7d53f31a_WHM-6R
Classic Boomhammer, 2 weapons so its not complicated, don't have to worry about heat or lock on.
Advanced Build -
https://mwo.nav-alph...10738024_WHM-6R
Still a brawler, but now the DPS has increased along with the heat
Alternate Mid to Long Range Build
https://mech.nav-alp...ca63e9b7_WHM-6R
2 Gauss and 4 ER Medium, still point a click, but getting the timing down on gauss charge can be a little tricky.
Bushwhacker P2
An underappreciated medium that can do a variety of builds, also tanky and with good hit boxes. Most builds revolve around some type of AC20 or Heavy Gauss with lasers. For longer Range it can also do Gauss + 2 Large Lasers + 2 ER Mediums for mid range poke
Starter Build -
https://mwo.nav-alph...b37c3c51_BSW-P2
Advanced Build -
https://mwo.nav-alph...98e2098a_BSW-P2
Urbanmech R-60 - A cheap light thats as tanky as most mediums, with a little work it can help turn the fight around and even has a chance against heavier opponents. Just don't go charging that Dire Wolf and you'll be fine.
Starter Build -
https://mwo.nav-alph...25175be6_UM-R60
Advanced Build -
https://mwo.nav-alph...ac8defc1_UM-R60
Clan Mechs
Huntsman - A good mix of speed and firepower, and with Omni capability it can run a variety of builds to fit any play style. I almost considered putting the Vapor Eagle here as it is an extremely powerful mech for its size, but its not very beginner friendly.
Sun Spider - Again a good mix of omni pods allowing for a variety of flexible builds. It plays better as a 2nd line mid to long range sniper than a close quarters combat mech. Most of the common builds take advantage of long range weapons. Again pick a target and apply pressure with your team.
Mechs to Avoid:
Shadow Cat - Unfortunately most new players do not know how to properly apply pressure, or have enough map awareness to play this mech. You'll either be caught out, or be the last mech alive with no hope of fighting off the opposing team.
Annihilator - Sure you have a lot of weapons, but you are a slow, giant target. Like the Shadow Cat you have to play the map with this mech to be sucessful, but it dosent have the escape tools to get away should you be caught out.
Pirahana - Glass cannon at its finest, but if anything so much as sneezes in your direction theres a good chance you're crippled.