Almost every game in patch 14.14-14.15 you want to be going phase rush, conqueror is not as viable nowadays due to lack of bruiser items that allow hecarim to tank damage and stay in the fight. Phase rush excels majority of the time due to needed mobility in the current meta and how it pairs with his most optimal items. Conqueror is still good if you see a team comp that is going to be constantly fighting you in melee range, or if you need to win early skirmishes.

Standard build with zekes is good almost every game but lethality is also solid if you want to "1v9" against squishy comps. If you are wanting to play it safe just go eclipse cleaver every game as that 2 item combo is incredibly overstatted, if you plan to go lethality get shojin second instead then build into opportunity -> seryldas. Finish off almost every build with deaths dance if enemy comp is AD, Maw if they are AP and steraks if they are mixed damage types. Deciding between building those 3 items are situational. For example if you build eclipse cleaver zekes and the enemy team comp has 3 AD and 2 AP, you should always build Deaths Dance in the scenario as a 4th item but 5th item can either be steraks or maw, prioritize steraks if fights are short with heavy cc, prioritize maw if fights go long with lower cc.