I can first-hand answer this.

Top status: in Hilton 60 nights, but IHG need 70 nights (or will the company allow you to buy/expense the cost of buying status-earning points on a stay 120k pts)? Hilton easier by nights, IHG easier if can buy those points whilst on a stay particularly at upper-end brands which offer 5k status-earning points

Lounges: generally depends on level of hotel that your company allows you to book, and ofc what level of properties exist where you travel to.
Hilton -- website on each property, displays icons including for Executive Lounge ...and "search criteria" for properties includes Exec Lounge
IHG -- written several times to IHG: CEO-level, regional Guest Relations, Rewards Dept and they : i. don;t have Lounge in search criteria ii. don't have a list of properties of Lounges ... i've switched mostly from IHG to Marriott ....workers at properties good, but IHG's Exec Mgmt just doesn't put features into its reservation system, also systems terrible eg. very poor integration with Mr & Mrs Smith which they lost to Hyatt