Ah well in my college not many people know about the series so I tend not to know what is popular and what is not exactly. 

Hajime no Ippo is an anime about a young fisherman boy who was picked on as a kid and was to weak to defend himself. One day by chance he happened to be in the way of champion class boxer Takamura on his morning jog. Ippo was being bullied and he was saved from the bullies by Takamura after he easily dodged the bullies punches but he also while doing so ripped off their coat buttons without noticing. Seeing that display Ippo decided that he would become a boxer like Takumura despite only being heavy enough for the Featherweight class. The anime follows his boxing adventures and the manga is still running today I believe since it started in the nineties. It is an anime I would recommend to nearly anyone. I won't say much more because I don't want to spoil the series.

Sekirei is an echhi anime with action except the ecchi gets either played up for comedy or is toned down later in the series. It follows a young boy named Minato who had just flunked out of his college entrance exam. By chance he runs into a girl named Musubi, whom is one of the one hundred some sekirei currently competing in the competition but she has yet to find a ashikabi (a master or lover) to fight for. After saving her life and standing up for her despite her hunters being winged sekirei and having electricity powers Minato kisses and by doing so winging Musubi (winging is done by a human with ashikabi genes kissing and causing the unlocking of the powers of the sekirei willing or not). Musubi saves the day and becomes Minato's first sekirei and promises they will win the competition so that they may stay together forever. 

It's not an anime I'd recommend to anyone like Ippo but it's a good anime as long as you can ignore the fan service.

As for Mobile Suit Gundam it's an amazing series and most anyone can get into it in someway or another if you even have a passing interest in mechs. Super robots fans can see G Gundam, Mobile Suit Gundam Wing while cliched and flawed at times is still one of Cartoon Networks most watched shows from back in the day and ranked just below Evangelion in Japanese polls back in the day, Gundam OO is a solid watch for a person wanting a mix of super and real robot action, Gundam's OVA's are all good watches, and shows like Gundam X and Turn A while lesser than the others are watchable. For anyone who wants a more light hearted take rather than war can see either of the gunpla based animes. And of course you can almost never go wrong with the original gundam series especially ones featuring Amuro Ray and his iconic rival Char Aznable. And you weren't wrong about gundam but not many people in the states know about it per say unless they're into anime while Japan has made a life size model of the RX- 78 Gundam (the original) and Char Aznable has reached Darth Vader status in Japan and he has numerous clones in not only gundam but in many anime and games alike so much you can look towards the Char Clone trope on TV Tropes.