A record 57% of marketers and agencies are allocating 20% or more of budgets to digital advertising, including 23% who earmark more than half of their spending for digital, according to the most recent in a series of studies published by RBC Capital Markets in partnership with Ad Age. Two percent said they plan to decrease their digital spend, while 82% said they plan to spend more, the study found.

Repondents again said they believed Google provided the best ROI, followed by Facebook, YouTube, Twitter, LinkedIn, Yahoo and AOL. Twitter was the only platform where respondents' perception of ROI declined since the prior survey, in September 2015.

Sixty-two percent of respondents said they plan to increase their spending on Facebook in the next year, compared with 54% for Google, 48% for YouTube and 32% for Twitter. Other respondents said they planned to cut spending on the platforms: 9% of respondents for Facebook, 10% for Google, 8% for YouTube and 23% for Twitter.

"Note that the overall skew of intentions does remain positive, with a greater percentage looking to increase rather than decrease their ad spend with Twitter," RBC wrote. "But taken as a whole, we view these results as clearly negative for Twitter, and perhaps the most negative data-point from this exercise."

A Twitter spokesman declined to comment on the study.

Asked about "emerging" platforms where they might allocate budgets next, respondents cited Instagram (71%), Snapchat (45%), Pinterest (42%), Spotify (34%), Pandora (27%), Hulu (27%), Google+ (18%), Tumblr (16%), Reddit (15%) and StumbleUpon (5%).

RBC surveyed nearly 2,000 advertising professionals for the study. Of them, 24% were a marketer or client, 36% worked for an agency, 10% were a marketing consultant, 13% worked for a media company, 7% work for a marketing-service company and about 8% were "other."