Marriott Gold should be better than SPG Gold, and it is. If removing the CC and airline (United Airlines) status giveaways and qualification perks for both Marriott and SPG, Marriott takes 50 nights to qualify, while SPG takes the quickest 10 stays or 25 nights.
On average, SPG Gold status members benefited more from the merger status match than Marriott Gold members. Marriott likely feared the loss of Starwood elite members, while they did not fear the loss of Marriott elite members leaving. At the end of the day, many SPG and Marriott elite members have more benefits than before the merger through status match. We have yet to see if there will be a dilution of room upgrades on either side now that there are more members.
If a Marriott Gold member is interested in lounge access at Starwood, the American Express SPG Business card offers lounge access at Sheratons. That won't help for Westins, Le Meridiens, or other brands, but it is an option for current Marriott members interested in SPG lounge access.