Another option is the autocannons with the lascannon sponsons. This is cheaper than the previous one but is for anti tank duty not general support. It is able to engage light and heavy armor. When you are on the move you will have to pick between the autocannon and lascannon. If you are firing at Armor 10 the autocannon is best. At armor 11 they both generate the same penetrating hits but the autocannon generates twice the glances so use the autocannon. For Armor 12 or above the lascannon is best. This tank might come in handy against squadrons of light vehicles like walkers or skimmers.
The final option is the all lascannon predator for anti heavy armor. This one rings in at over 160 points so is not a popular choice. I would probably only bring this for anti monolith duty where melta's are not effective or for opponents spamming nasties inside Landraiders where the stand off weapon range is important. This tank will generate .75 glances + .75 penetrates while stationary against AV 14 not to shappy. This compares to a single multimelta at close range with .1 glances and .4 penetrates assuming 2d6 armor penetration.