United are still a very attractive club for the vast majority of players. Are we the destination of choice for the creme de la creme ? Probably not, to be fair. These things often go in cycles (evidenced by the downfall of Milan and Internazionale and even Juventus) - and from a purely footballing perspective, we have declined just a tad in terms of appeal, unlike the Fergie years. Right now Real Madrid and Barcelona are in a different class altogether (especially for Latin American and Southern European players) from almost every perspective, and realistically United can't always match that in the short or even long term, given the propensity of Madrid and Barcelona to always attract the best of the best even back in the day (especially the former). But those two can't sign every major player, and we should be there or thereabouts for the rest of the elite. If Manchester City of all clubs can swopp in like a vulture for the likes of Sergio Aguero or David Silva (who were approaching world class status at Atletico and Valencia), then there's no reason to believe United can't do the same given our much superior history, track record of success (once the club becomes more stable), and finances ( in the FFP era).
Losing the greatest manager of the modern era has put a dent in our chances for silverware/ footballing appeal, that's undeniable. Van Gaal is not Fergie by any stretch of the imagination, and his reputation as an almost dictatorial and uncompromising task-master (as opposed to Fergie's harsh but more warm and humane Papa-bear approach) might even ward some players off. But to kind of counterbalance that, Fergie didn't sign a lot of marquee players anyway, and Woodward and the owners are now willing to pump unprecedented amounts of money into the club. Massive wages aren't everything for certain players, but by and large, that along-with agent/ intermediary fees does tend to lubricate the negotiations to a degree - as evidenced by the success of Oligarch/ Sheikh bankrolled clubs.
To be honest, we were a bit hurt by the transfer policies of David Gill and even Fergie. Both of them were kind of old school in their ideology and didn't have much time for agent conventions (United was a non-attendee at a lot of agent fairs), or the newer age 'Show me the money ! type super-agents who were more into networking for mutual benefit and extracting more commissions, which is where some of the other major clubs pulled ahead. Woodward doesn't share that feeling of underlying contempt, he seems more suave and approachable from that perspective, and is reportedly well connected, and on good terms with a lot of handlers. Apart from that, the most important thing IMO is bringing United back to a point where the club is regularly contending for the League title and the latter stages of the European Cup. If we go on a run of consecutive semi-final appearances in the Champions League to go with 1-2 finishes in the league, the club once again becomes a major attraction for players. That will ensure that there's a better balance of priorities - players are joining United for more of the right sporting reasons, rather than just wads of cash. Until that happens, we will have to overpay to an extent.
I think once we becomes more successful, United is in Bayern Munich's ballpark in terms of attractiveness, and probably a bit better than them overall. Pragmatically speaking, neither club can always contend with Madrid and Barcelona's appeal for the absolute top players, but are just a notch below. Both storied teams with a rich history of success. Both able to afford massive fees and wages, based on their financial status (infact United have an edge in there both right now, and the future). Is Munich a more desirable city to live in ? Probably yes. But conversely, the English League is more attractive and marketable. So, like them, we should be able to attract world-class players at decent rates. But that's all predicated on success to a large degree. Will that happen under Louis ? Dunno. But he should be able to elevate our performances on a year-by-year basis, and is more of a short-term patchwork appointment IMO. So our next managerial appointment could be critical for the medium to long-term appeal of the club.