Everybody is recommending dark beers since you enjoyed Guinness but I would maybe recommend trying some lighter styles, especially some sour beers. If you are coming from ciders you might find a lot of similarity in sour beers. Sour beers can be extreme, like a Berliner weisse, which is very sour with almost no bitterness. They can also be very mild. My favorite style of beer is a Flanders ale which has a lot of malt richness paired with a nice mild sour finish. You might like a gose which is usually mildly sour, slightly salty, crisp and refreshing. Very cider-like. The main thing is don't let one beer turn you off from that style. Try everything and figure out what you like. Most beer pubs will let you sample beers before you purchase them. Don't be afraid to try something different because you never know what you will like. I hated pilsners for years and refused to drink them, then one day I had one and they are now it's one of my favorite styles of beer.